Focal lesions in the splenium of the corpus callosum in patients with epilepsy

Predictive factors of de novo epilepsy in reversible splenial lesion syndrome

PURPOSE

Reversible splenial lesion syndrome (RESLES) is a rare neurological disorder in East Asia with good prognosis. Herein, we investigated the predictive factors for de novo epilepsy in RESLES.

METHOD

This single-centre cohort study was conducted at Sendai Medical Center in Japan, enrolling patients with RESLES without previous epilepsy treated between February 2008 and May 2023 with follow-up for at least 1 month. The outcome was de novo epilepsy during or after RESLES without other aetiologies of epilepsy. The variables during RESLES admission were compared between patients with (Group A) and without (Group B) de novo epilepsy. Statistical analyses were performed using the Mann-Whitney U or Fisher's exact tests.

RESULT

Twenty-two patients (males 11/22; 50 %) met the inclusion criteria. The mean age and median follow-up duration were 37 ± 20 years and 35.9 months (range: 2.4 to 199 months), respectively. The aetiologies included infection (10/22, 45.5 %), cerebrovascular disorders (3/22, 13.6 %), and others (8/22, 36.4 %). Acute symptoms included fever (14/22, 63.6 %), altered mental status (19/22, 86.4 %), seizures (8/22, 36.4 %), and status epilepticus (2/22, 9.1 %). MRI showed splenial lesions (mean vertical length 7.0 ± 1.7 mm and mean horizontal length 14.2 ± 7.6 mm) and extra splenium lesions of corpus callosum (1/22; 4.5 %). 9.1 % (2/22) developed de-novo epilepsy. Status epilepticus (2 vs 0; p = 0.001), long horizontal splenial lesions (24.7 mm vs 13.2 mm; p = 0.04), use of anti-seizure medication (3 vs 2; p = 0.04) were significantly more common in Group A than B.

CONCLUSION

Status epilepticus during the acute phase of RESLES may predict the development of epilepsy.

Toxic leukoencephalopathies

Toxic-metabolic encephalopathies are a group of disorders in which an exogenous or endogenous substance leads to transient or permanent neuronal damage. It is an important cause of potentially reversible acute encephalopathy syndrome. The signs and symptoms of toxic encephalopathies may be relatively nonspecific, and toxicologic tests are not always widely available. Imaging plays a key role in determining the most probable diagnosis, pointing to the next steps of investigation, and providing prognostic information. In this chapter, we review the main acquired toxic-metabolic leukoencephalopathies, commenting on their pathophysiology, imaging patterns, and rationale for an adequate diagnosis in detail.

Reversible splenial lesion after surgery for distant arteriovenous malformation: a case report

Isolated lesions of the corpus callosum are rare and may represent permanent but also transient responses to various pathology termed "reversible splenial lesion syndrome" (RESLES) when in light of relevant clinical presentation. We present the first case of the RESLES after elective surgery for distant arteriovenous malformation (AVM), followed by a slight speech disturbance and MRI verified small, oval, well-circumscribed area of apparent cytotoxic edema in the center of the corpus callosum splenium, which completely resolved within 15 days. Surgery for AVM is followed by the complex adaptation to a new vascular pattern, RESLES might develop, and should be suspected.

Splenial Lesions in Benign Convulsions With Gastroenteritis Associated With Rotavirus Infection

OBJECTIVE

To investigate clinical risk factors for acute magnetic resonance imaging (MRI) abnormalities in patients with benign convulsions with mild gastroenteritis or benign infantile epilepsy.

STUDY DESIGN

We investigated clinical and diffusion-weighted imaging findings in 32 patients with benign convulsions with mild gastroenteritis and 22 patients with benign infantile epilepsy who underwent MRI within seven days of seizure onset between 2010 and 2015.

RESULTS

Diffusion-weighted imaging showed signal hyperintensity in the splenium of the corpus callosum in seven patients with benign convulsions with mild gastroenteritis, but no abnormalities in patients with benign infantile epilepsy. Patients with benign convulsions with mild gastroenteritis with splenial lesions showed a higher rate of rotavirus detection from feces (P = 0.006), higher serum level of C-reactive protein (P = 0.04), and shorter interval between seizure onset and MRI (P = 0.002) than patients with benign convulsions with mild gastroenteritis without splenial lesions. Multivariate analysis revealed rotavirus infection as a significant risk factor for splenial lesions on diffusion-weighted imaging in patients with benign convulsions with mild gastroenteritis (P = 0.02).

CONCLUSIONS

Splenial lesions are often seen during acute period in patients with benign convulsions with mild gastroenteritis. Rotavirus infection is a risk factor for splenial lesions in patients with benign convulsions with mild gastroenteritis, suggesting the role of rotavirus to cause edema in the corpus callosum. From our observations, benign convulsions with mild gastroenteritis with a splenial lesion on diffusion-weighted imaging suggests good outcomes, and extensive evaluation of these patients may be unnecessary.

Reversible Splenial Lesion Syndrome Associated with Encephalitis/Encephalopathy and Hyponatremia

Reversible splenial lesion syndrome (RESLES) is a rare occurrence with a broad clinical and radiological spectrum due to several conditions and diseases. Generally, clinical symptoms of RESLES include mildly altered states of consciousness, delirium, and seizures. RESLES can be shown in conjunction with central nervous system infections, especially in children. Hyponatremia is also described as a potential cause of reversible splenial lesions. Reversible signal changes on diffusion-weighted images are detected in patients for diagnosis. The prognosis is usually good but it depends on the underlying disease, neurological and imaging findings. Here we present two pediatric patients with RESLES accompanied by hyponatremia.

Reversible splenial lesion syndrome in children with benign convulsions associated with mild gastroenteritis: A retrospective study of five cases

OBJECTIVE

To assess the clinical and imaging features of reversible splenial lesion syndrome (RESLES) with benign convulsions associated with mild gastroenteritis (CwG) in children.

PATIENTS AND METHODS

We retrospectively reviewed the clinical course, blood and stool examinations, cerebrospinal fluid (CSF) examination, magnetic resonance imaging (MRI), electroencephalography (EEG) findings, therapy and prognosis of five children with RESLES associated with CwG.

RESULTS

Five previously healthy patients, four girls and one boy, with mean age 26.4 ± 8.1 months, had clusters of general tonic-clonic or clonic seizures within the first two days of gastroenteritis. Rotavirus antigen was positive in the stool of one case. Interictal EEG was normal except in one case, which showed occipital slow wave. The initial MRI was performed within five days of onset, four patients had an isolated lesion in the splenium of the corpus callosum (SCC), and one patient had lesions extending outside the SCC that involved the genu of the corpus callosum. The follow-up MRI was performed 10-15 days after onset, and all lesions had completely disappeared. All patients were treated with antiviral, rehydration and anticonvulsant therapy in the acute phase. They had good prognosis and normal psychomotor development, with no neurological sequelae after 26-30 months of follow-up.

CONCLUSIONS

CwG and RESLES can coexist in young children. The patients present with clusters of general tonic-clonic or clonic seizures in the acute phase. Brain MRI shows focal lesion in the SCC with high signal intensity on T2-weighted and FLAIR sequences. It has good prognosis and excessive treatment is not necessary.

The spectrum of peri-ictal MRI changes; four illustrative cases

PURPOSE

Seizure induced neuronal hyperexcitability and increased unmet metabolic neuronal demand results in failure of the sodium/potassium ATP pump. Sodium and water accumulates intracellularly with cellular swelling and reduced extracellular volume demonstrating hyperintensity on DWI and reduced ADC. The aim of this study was to describe 4 clinical cases where we identified abnormalities in diffusion restriction in the acute peri-ictal period and followed them longitudinally.

METHODS

Patients were recruited from the emergency department, clinical consultation service and epilepsy monitoring unit of two tertiary referral centres. Patients underwent either 1.5T or 3.0T MRI with DWI, ADC, T2-weighted and post contrast studies during their acute admission and again after a period of follow up.

RESULTS

Four patients were identified as having visible diffusion restriction and reduced ADC in one or both hippocampi and the splenium of the corpus callosum. These lesions either completely resolved, showed interval improvement or demonstrated atrophy on follow up imaging. The two patients with persisting abnormalities had presented with status epilepticus.

CONCLUSIONS

These acute ictal imaging changes give clinicians an important in-vivo look at the dynamic neuronal metabolic environment in the peri-ictal period. Areas that appear most susceptible include the mesial temporal structures and corpus callosum. Close imaging follow up to document resolution or evolution of long lasting sequelae is vital. There is no clear consensus as to why some patients develop ictal related imaging changes and others do not. Seizure length and time interval from ictus to scan appear to play a role but larger prospective studies are needed to confirm this.

An exploration of the spectrum of peri-ictal MRI change; a comprehensive literature review

PURPOSE

The aim of this review was to identify published studies in the literature relating to ictal induced MRI change and to identify certain common themes, practical points for clinicians and areas for future research.

METHODS

We identified 96 articles that satisfied our inclusion criteria yielding 575 cases. All articles were analysed; number of subjects, spectrum of MRI and EEG change, aetiology, and follow-up (both clinical and imaging) were noted.

RESULTS

The most frequent imaging changes were restricted diffusion, T2-hyperintensity and reduced ADC values. The mesial temporal structures and neocortex were most commonly affected locations though subcortical structures like the thalamus and pulvinar were also described. Practical clinical points included; the development of PLEDS concordant with ictal imaging change was associated with worse clinical prognosis, patients with seizures due to symptomatic aetiology may be more likely to develop ictal related imaging change and follow up is vitally important to ensure that ictal related oedema is not misidentified as a mass lesion or conversely that a mass lesion is not misidentified as ictal related change.

CONCLUSION

Qualitative MRI studies have provided clinicians with useful in-vivo insights into the dynamic ictal neuronal environment. Changes are not only localised to the ictal focus but can be remote and irreversible. Small patient numbers varying study design and high numbers of symptomatic seizures makes comparison between studies problematic. Also there is possible microstructural quantitative MRI changes that are missed on qualitative MRI. There is a need for prospective quantitative MRI studies in patients with epilepsy peri-icatlly with a uniform period of follow up and comparison to control data.

Drug taper during long-term video-EEG monitoring: efficiency and safety

OBJECTIVES

Anti-epileptic drugs (AED) are often tapered to reduce the time needed to record a sufficient number of seizure during long-term video-EEG monitoring (LTM). Fast AED reduction is considered less safe, but few studies have examined this. Our goal is to examine whether the rate of AED reduction affects efficiency and safety.

MATERIALS & METHODS

We performed a retrospective observational study of patients referred for presurgical evaluation. Each patient was categorized by two dichotomous parameters of AED tapering: (i) fast vs slow AED reduction the first 24 h of LTM and (ii) complete vs partial AED discontinuation during LTM.

RESULTS

Of 79 patients, 51% underwent a fast AED reduction and 58% ended up with AEDs completely discontinued. Complete AED discontinuation was associated with three times increased likelihood of receiving rescue therapy during LTM and double risk of having secondary generalized tonic-clonic seizures (sGTCS) compared to the group partially discontinued. Fast vs slow AED reduction had no effect on the safety of LTM. The fast AED reduction group and the complete AED discontinuation group had a significantly longer time to first seizure and total recording time compared to the slow AED reduction and partial discontinuation groups, respectively.

CONCLUSIONS

Fast AED reduction was found safe in patients undergoing presurgical video-EEG monitoring. Patients completely discontinued from AEDs had more sGTCS than patients partially discontinued. Further studies are suggested to confirm this finding and to evaluate whether fast reduction is safe and efficient in other subgroups of patients referred for LTM.

Clinical manifestations in children and adolescents with corpus callosum abnormalities

Corpus callosum abnormality (CCA) outcomes are quite unpredictable and variable, from asymptomatic forms to mild or severe neurodevelopment disorders. The aim of this study was to examine clinical outcomes in CCA patients. The study included 61 children and adolescents in whom brain magnetic resonance imaging (MRI) scans showed CCA, isolated or associated to other central nervous system lesions. All patients underwent anamnesis, physical and neurological examination, routine laboratory tests, electroencephalogram (EEG), and MRI scans. In all participants, the intelligence quotient (IQ) was determined. We divided the participants into two subgroups: the first subgroup included patients with an isolated CCA, and the second subgroup included patients with CCA associated with extra-callosal brain lesions (complex CCA). We found that CCA were associated with elevated frequency to intellectual disability (ID), other neurodevelopment disorders, epilepsy, and isolated EEG anomalies. Mild ID (p = 0.003) was more frequent in the isolated subgroup, while epilepsy (p = 0.036) and pre-perinatal risk factors (p = 0.023) were more frequent in the complex CCA subgroup. Although the role of the CC in the interhemispheric communication is known, neurological and neurodevelopment outcomes of CCA are extremely variable and unpredictable. The presence of extra-callosal brain anomalies is one of the major prognostic factor, and probably, they have an important impact on the clinical outcome.

Postictal MRI abnormalities and seizure-induced brain injury: notions to be challenged

OBJECTIVE

This was a bibliographic search to address the quality of evidence in clinical reports supporting the assertion that brain MRI signal abnormalities are a direct consequence of seizures.

METHODS

The search on PubMed was performed by applying the following inclusion criteria: a) original case reports, b) in humans, c) as single case reports or series of patients, d) of visually detected acute MRI signal abnormalities, e) attributable directly to seizures, and f) published in English. Bibliographic references of initially selected publications were reviewed for additional articles. Full texts of selected publications were read for information regarding clinical, EEG, and MRI features. Moreover, claimed evidence supporting seizure-induced excitotoxicity was assessed.

RESULTS

The search resulted in 91 publications corresponding to 413 cases. There was a wide range of clinical features and EEG and MRI abnormalities. Premorbid or comorbid conditions were present in many cases, and some of them are potential causes of MRI changes. Claimed evidence for MRI signal abnormalities as a direct consequence of ictal activity was mostly based on the similarity with previous reports, animal models, reversibility, congruent EEG, MRI changes not respecting vascular territories, and ruling out other etiologies.

CONCLUSIONS

Evidence supporting the notion of seizure-induced excitotoxicity is questionable in the studied reports of postictal MRI abnormalities.

Transient lesion in the splenium of the corpus callosum due to rotavirus infection

Transient signal changes in magnetic resonance imaging (MRI) of the splenium of the corpus callosum (SCC) can result from many different reasons, including encephalitis and encephalopathy caused by infection, seizures, metabolic disorders and asphyxia. We report a case of a 6-year-old Polish girl with rotavirus infection demonstrating a reversible SCC lesion on diffusion-weighted MRI images. She presented six episodes of generalized tonic seizures with mild acute gastroenteritis. Stool test for rotavirus antigen was positive. At the time of admission imaging showed the hyperintense region in T2-weighted and fluid-attenuated inversion-recovery MRI, a well-defined lesion in the splenium of the corpus callosum with restricted diffusion in diffusion-weighted MRI and no enhancement in post contrast T1-weighted imaging. Her first EEG showed slow brain activity in the posterior occipitotemporal portion, consisting mainly of theta waves with a frequency of 4.5-5.5 Hz and amplitude of 40 uV. The lesion had completely disappeared on follow-up MRI 10 days later. The patient recovered fully without any sequelae.

Clinical and Neuroimaging Profile of Children with Lesions in the Corpus Callosum

PURPOSE

T2-hyperintense signal changes in corpus callosum (CC) have been described in epilepsy and encephalitis/encephalopathy. Little is known about their pathophysiology. The aim of this study was to examine the clinical presentation and evolution of CC lesions and relationship to seizures.

METHODS

We identified 12 children among 29,634 patients from Radiology Database. We evaluated following characteristics: seizures and accompanying medical history, antiepileptic drug usage, presenting symptoms, and radiological evolution of lesions.

RESULTS

CC lesions were seen in patients with prior diagnosis of epilepsy (n = 5) or in those with new onset seizures (n = 3), or with encephalitis/encephalopathy without history of seizures (n = 4). Seizure clustering or disturbances of consciousness were the main presenting symptoms. No relationship was observed between CC lesion and AEDs. On imaging, ovoid lesions at presentation resolved on follow up imaging and linear lesions persisted. DTI showed that the fibers passing through splenial lesions originated from the posterior parietal cortex and occipital cortex bilaterally.

CONCLUSION

In patients with seizures, no clear relationship was demonstrated between seizure characteristics or AED use with CC lesions. Ovoid lesions resolved and may have different pathophysiologic mechanism when compared to linear lesions that persisted.

Corpus callosum and epilepsies

Introduction.Corpus callosum (CC) is the largest forebrain commissure. Structural anomalies and accompanying clinical symptoms are not in the focus of neurologists, epileptologists or neurosurgeons.

Aim and method.Anatomy, embryological development, normal functions, structural abnormalities, additional malformations, clinical symptoms and seizure disorders with CC anomalies are reviewed from the literature.

Review.The detection of callosal anomalies increased rapidly with widespread use of brain imaging methods. Agenesis or dysgenesis of corpus callosum (AgCC) might be considered an accidental finding. Epileptic seizures occur in up to 89% of patients with AgCC. The causal relationship correctly is questioned. However, additional causative malformations of midline and/or telencephalic structures can be demonstrated in most seizure patients. The interruption of bilateral spread of seizure activities acts as the concept for callosotomy as epilepsy surgery. Indications are drug-resistant generalized, diffuse, or multifocal epilepsies. A resectable seizure onset zone should be excluded. Most treated patients are diagnosed as Lennox-Gastaut or Lennox-like syndrome.

Conclusions.In cases with callosal abnormalities and clinical symptoms additional malformations are frequently observed, especially with seizure disorders. Callosotomy is the most effective option against drop attacks. The method probably is underused. After callosotomy a circumscript seizure focus might be unveiled and a second step of resective epilepsy surgery can be successful.

[Transient splenial lesion in influenza A H1N1 2009 infection]

Severe neurologic complications have been rarely reported during novel pandemic influenza A(H1N1) virus infections. We describe the case of an 10-year-old boy with new onset seizures and proven influenza A(H1N1) 2009 infection showing a reversible hyperintense lesion in the splenium of the corpus callosum on T2-weighted and FLAIR magnetic resonance images without contrast enhancement. Transient splenial lesions have been described in the context of virus encephalopathy and do not require specific treatment.

Transient splenial lesion of the corpus callosum in a case of benign convulsion associated with rotaviral gastroenteritis

Transient magnetic resonance (MR) signal changes in the splenium of the corpus callosum (SCC) arise from many different conditions, including encephalopathy or encephalitis caused by infection, seizures, metabolic derangements, and asphyxia. Few case reports exist on reversible SCC lesions associated with rotavirus infection. A benign convulsion with mild gastroenteritis (CwG) is frequently associated with rotaviral infections. This entity is characterized by normal laboratory findings, electroencephalogram, neuroimaging, and good prognosis. We report a case of a 2.5-year-old Korean girl with rotavirus-associated CwG demonstrating a reversible SCC lesion on diffusion-weighted MR images. She developed 2 episodes of brief generalized tonic-clonic seizure with mild acute gastroenteritis without any other neurologic abnormality. Stool test for rotavirus antigen was positive. Brain MRI done on the day of admission showed a linear high signal intensity and decreased apparent diffusion coefficient values on the SCC. The lesion completely disappeared on follow-up MRI 6 days later. The patient fully recovered without any sequelae.